code: def ref_func_binary_tanh(x):
      # Binary tanh, value @x==0 is set to -1
      return 2 * np.round(np.clip((x + 1) / 2, 0, 1)) - 1
  
file_path: nnabla/python/test/function/test_binary_activation.py
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import function_tester, list_ctx_and_func_name
label_desc: Use image node_id 1 for calling a global function with example usage: ref_func_binary_tanh(x) and returns: unknown